// Change elements public void SwapControl(int line, int controlNum, Control newControl) { LayoutElement lElement = elementList?[line].GetElement(controlNum); if (lElement == null) { throw new ArgumentException("The element doesn't exist"); } GridElement gElem = lElement as GridElement; if (gElem != null) { gElem.control = newControl; } else if (lElement is BlankElement) { throw new NotSupportedException("Feature is not yet working"); } else { throw new InvalidOperationException($"Unknown element type in List: {lElement.GetType().Name}"); } }